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Sandy Srinivas, MD
Sandy Srinivas, MD
Posted: Monday, February 27, 2023
Based on the primary analysis of the multicenter FORMULA-509 trial, which was presented during the 2023 American Society for Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (Abstract 303), adding abiraterone acetate plus prednisone and apalutamide to standard-of-care salvage radiotherapy and androgen-deprivation therapy failed to significantly improve progression-free and metastasis-free survival outcomes in patients who had high-risk features and detectable prostate-specific antigen (PSA) levels after radical prostatectomy. However, Paul L. Nguyen, MD, MBA, of the Dana-Farber Cancer Institute, Boston, and colleagues suggested those with higher PSA levels may benefit from this regimen.
Patients were randomly assigned to receive 6 months of treatment with abiraterone acetate plus prednisone and apalutamide (n = 173) or bicalutamide (n = 172) in combination with salvage radiotherapy and 6 months of androgen-deprivation therapy with a gonadotropin-releasing hormone agonist; of this population, 332 were deemed evaluable. At a median follow-up of 34 months, the 3-year progression-free survival rate was higher with abiraterone acetate plus prednisone and apalutamide than with bicalutamide (74.9% vs. 68.5%; hazard ratio [HR] = 0.71; one-sided P = .06). The 3-year metastasis-free survival rates were 90.6% and 87.2%, respectively (HR = 0.57; one-sided P = .05).
A subgroup analysis revealed significantly superior 3-year progression-free (67.2% vs. 46.8%; HR = 0.50; two-sided P = .03) and metastasis-free (84.3% vs. 66.1%; HR = 0.32; two-sided P = .01) survival outcomes with abiraterone acetate plus prednisone and apalutamide versus bicalutamide in patients with a PSA level above 0.5 ng/mL. Neither patients with a PSA level of 0.5 ng/mL or lower nor those with pN0 or pN1 disease appeared to demonstrate a statistically significant benefit.
According to the investigators, the adverse events were consistent with the known safety profiles of the investigational agents. Rash and hypertension were reported more frequently with abiraterone acetate plus prednisone and apalutamide.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
2023 ASCO GU Cancers Symposium
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